"We all devour each other, in our fashion," Tennessee Williams once said in an interview. The act of devouring in the playwright's 1958 "Suddenly Last Summer" means several things. In a new, transfixing production of the work by Theatre 9/12, the consuming of human vitality out of banal self-interest is made stunningly unholy.

Directed with his usual sure-handedness at balancing rich, tonal colors, 9/12 co-founder Charles Waxberg cultivates and intertwines the genteel manners, seething rage, moral duplicity and cathartic release Williams tightly packs within a one-act mélange of psychological horror. On a handsome set depicting the garden of a New Orleans mansion — the garden's walls metaphorically covered with the grasping tension of creeping vines — "Suddenly Last Summer" is already at a low boil in its opening moments.

Actress Lisa Carswell, playing the wealthy widow Mrs. Venable, lulls the audience and the visiting Dr. Cukrowicz (Joey Fechtel) with honeyed dignity before unleashing her character's perverse protectiveness of a gilded memory. That remembrance concerns Mrs. Venable's late son, Sebastian, who died mysteriously in Spain the previous summer — an event witnessed by her unstable niece, Catharine (Sarah Milici). Catharine is tucked away in an asylum but speaking fitfully about the dark incident she saw, which contradicts Mrs. Venable's insistence that Sebastian, despite evidence to the contrary, was a chaste poet.

When the dowager presses Cukrowicz to perform a lobotomy on Catharine in exchange for a grant the doctor seeks, Fechtel looks as if his character wants the earth to swallow him. Kate Szyperski and Eric Olson, as Catharine's mother and brother, are equally effective with their own ethical challenges.

The show's final stretch belongs to Milici's feverish tour de force, her Catharine a whirlwind of trauma, sensuality, keen intelligence and coltish rebellion. Floating in a soft summer dress, the actress yanks on the monstrous truth locked in Catharine's beleaguered frame, the resigned heroine aware every onlooker has reason to crush her. It's a seamless performance that is something to see.

Tom Keogh: tomwkeogh@gmail.com